#include <fstream>
    #include <cstring>

    class Reference
    {
        std::ostream &d_out;

        public:
            Reference(std::ostream &out)
            :
                d_out(out)
            {}
            void swap(Reference &other)
            {
                char buffer[sizeof(Reference)];
                memcpy(buffer, this, sizeof(Reference));
                memcpy(static_cast<void *>(this), &other, sizeof(Reference));
                memcpy(static_cast<void *>(&other), buffer,
                                                    sizeof(Reference));
            }
            std::ostream &out()
            {
                return d_out;
            }
    };

    int main()
    {
        std::ofstream one{ "one" };
        std::ofstream two{ "two" };

        Reference ref1{ one };          // ref1/ref2 hold references to
        Reference ref2{ two };          // the streams

        ref1.out() << "hello to 1\n";   // generate some output
        ref2.out() << "hello to 2\n";

        ref1.swap(ref2);

        ref2.out() << "hello to 1\n";   // more output
        ref1.out() << "hello to 2\n";
    }